Feed-back oscillator using ionizing tube



July 31, 1934. HUND 1,968,770

FEED-BACK OSCILLATOR USING IONIZING TUBE Filed July 6, 1932 INVENTOR Angus: Humil Patented July 31, 1934 1,968,770 PATENT @FFECE FEED-BACK OSCILLATOR USING IONIZING TUBE August Hunfl; West Orange, N. J., assignor to Wired Radio, Inc., New York, N. Y., a corporation of Delaware Application July 6, 1932, Serial No. 621,005

Claims.

This invention relates to electrical Oscillator systems and more particularly to feed-back oscillator circuits. using glow discharge tubes which have no filament excitation.

An object of my invention is to provide a feedback oscillator suitably adapted to a filamentless tube.

Another object of my invention is to so arrange the elements of the oscillator system in relation to one another that a stable and otherwise dependable source of oscillations may be obtained.

Another object is to provide a feed-back oscillator having a glow tube which exhibits both primary and secondary ionization, as distinguished from heretofore known types of glow tubes in which primary ionization alone was permissible.

The novel featureswhich I believe to be characteristic of my invention are set forth with particularity in the appended. claims. My invention,'itself, however, together with its objects and advantages, may best be understood by reference to the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a feed-back oscillator circuit diagram which exhibits the principles of my invention; and I Fig. 2 is a modified feed-back oscillator circuit diagram of my invention.

Referring to Fig. l, I show a gaseous discharge tube l'which comprises four electrodes, 2, 3, 4 and 5, enveloped in a suitably attenuated gas or mixtureof gases. Electrodes 2 and 3 are used for setting up a primary ionization discharge,

. simple wire ring. 'Interposed between the anode 4 and the ionizing electrodes is a control electrode 5 which, if desired, may be in the form of awire helix. The exact structural arrangement of the electrodes of an ionizing tube of this chara'cter necdnot necessarily be as herein shown,

but other forms of construction have been found to be{s'uitable. Severalembodiments of glow tubes, for example, are shown and described in my copending application; Serial No. 624,920, filed July 27, 1932. a A direct current for setting up an ionization discharge between the electrodes 2 and 3 is de rived from the source 6, the ionizing circuit including a protective resistance '7, having an adjustable tap 19. i If desired, a current indicator 8 may be used as shown in this circuit. From a tap 9 which is adjustably disposed along the resistance 7 current is also fed to a work circuit which includes the work anode 4 and the ionizing anode 3. This work circuit current may, if desired, be measured by means of the current indicator 10. Between the current indicator 10 and the work anode 4 is a tank circuit comprising an inductance 11 shunted by a variable condenser 12. If desired, the point of connection towards the positive pole of the battery may be varied by means of an adjustable contact 13, or a suitable tap associated with the inductance 11. This is for the purpose of obtaining a maximum of output power.

Coupled to the inductance 11 is a feed-back circuit including an inductance 14 which is connected at one end to the control electrode 5 and at the other end with a source of bias potential 15 whereby the control electrode 5 may, if desired, be rendered more negative than the ionizing anode 3. A suitable condenser 16 may be employed to by-pass variable currents around the resistance '7 and another condenser 1'? may be similarly employed to by-pass variable currents around the battery 15. Still another condenser 18 may be used optionally as a by-pass around the battery 6 but the capacitance of this condenser must be such that no relaxation oscillations are set up in the ionizing circuit.

In the operation of my invention according to Fig. 1, primary ionization takes place between the electrodes 2 and 3. It will be understood that the tube construction, the kind of gas, or mixture of gases, and the pressure within the envelope of the tube are determining factors in controlling the extent both of the primary glow and the secondary glow as mentioned in the objects of this invention. Further discussion, however, of the structural details of the tube itself is reserved for presentation in the aforementioned copending application, Serial No. 624,920. It is sufficient here to state that negative ions, (mostly electrons) are projected through the openings in the control electrode 5 and toward the work anode 4. The drop of potential in the resistance '7 between the taps 9 and 19 creates a corresponding potential drop from the work anode 4 to the ionizing anode 3. Due to the high positive potential applied to the work anode 4, secondary ionization takes place in the space intervening between the electrodes 5 and 4. The current set up inthe work anode branch is therefore greatly increased over that which would result in the absence of work anode ionization, that is, secondary ionization. Thus it is possible by means of varying the potential applied to the control electrode to control considerably more power than when operating such a tube under the heretofore assumed limitations of primary ionization, that is, far from the saturation point. The cir- Ill) Iii-u cuit being regenerative, any transient currents occurring in the tank circuit 1l12, will excite the feed-back circuit which includes the inductance l4 and the control electrode 5. The variation of potential on the electrode 5 with respect to the work anode 4 will produce amplified variations of current in the work anode and tank circuit with the result that oscillations will very quickly be built up to a self-sustaining degree. The frequency of the oscillations may, of course, be adjusted by means of th variable condenser 12 and by the choice of constants otherwise used in the circuit.

Referring to Fig. 2, a circuit diagram is shown which in many respects is similar to that of Fig. l. The principal modification, however, consis s in providing a parallel feed arrangement. The direct current circuit from the battery 6 to the work anode 4 is in parallel with the inductance 20, and by virtue of the condenser 21 no direct current can traverse this inductance. A hi h frequency choke 22 also to prevent variable currents from traversing the battery 6.

The bia for the con rol electrode 5 may in this case be derived from a potentiometer 24 having an adjustable tap 25. As another modification, the variable condenser 23 connected. across the control electrode 5 and work anode i. The by-passing condensers l7 and 18 may be used in the same manner as heretofore described in connection with Fig. 1.

The operation of the circuit shown in Fig. 2 is as follows:

Primary ionization takes place between the electrodes 2 and 8. Secondary ioi ization occurs in the region of the work circuit anode l due to the high potent-iai which is impressed thereon. Any transient currents which may tend to upset the equilibrium of the put circuit, including the inductance 2C are inductively reflected int the input circuit through the inductance 14, whereupon the potential of the control electrode is varied. Amplification of current variations then takes place in the output circuit, including the work circuit anode and oscillations will be built up through the interaction of the input and output circuits to the point where they will be self-sustained. It will, of course, be understood that the circuit constants of the oscillator shown in Fig. 2 adjusted in accordance with the frequency to be obtained.

To those skilled in the art, other modifications of my invention will be suggested by the foregoing disclosure. I do not wish, therefore, to be limited to the, specific modifications herein shown but only in accordance with the appended claims I claim:

1. In an oscillator system a partially evacuated envelope, a pair or; primary ionizing electrodes within said envelope, a control electrode, a work anode, said control electrode and said work anode being substantially circular and co-axially disposed with respect to said primary ionization electrodes, means including said primary ionizing electrodes for producing therebetween a primary region of ionization activity, means including said control electrode and said work anode for producing th rebetween a secondary region of ionization activity substantially enclosing said primary ionization region and means for producing regeneration only between the electrodes utilized for producing one of said regions of ionization activity.

2,. An oscillation system comprising, a partially evacuated envelope including therein a pair of primary ionizing electrodes, a control electrode and a work anode, said control electrode and work anode substantially encircling said primary electrodes, means for energizing said primary ionizing electrodes to produce therebetween a primary region of ionization activation, means for energizing said control electrode and work anode to produce under control of said primary ionization activation a secondary ionization activation therebetween, and a circuit interconnecting said control electrode and work anode for producing sustained oscillations in said secondary ionization activation area only.

3. An oscillation system comprising, an envelope having an attenuated atmosphere therein, a pair of primary ionization electrodes, 21. control electrode and a work anode in said envelope, said control electrode and said work anode substantially encircling said primary ionization electrodes, means for establishing a potential difference between said primary ionization electrodes for producing a primary region of ionization therebetwcen, means for establishing a difference of potential between said other electrodes for producing a region of secondary ionization between said control electrode and said work anode for co-action with said primary ionization and means inductively coupling said control electrode and work anode to produce a regenerative eifect for establishing sustained oscillations in said secondary ionization area only.

i. An oscillation system comprising, an envelope having an attenuated atmosphere therein, a pair of primary ionization electrodes, a circuit connected between said primary electrodes and including a source of energy for establishing a difference of potential between said electrodes to produce a primary region of ionization therebetween, a control electrode and a work anode, at least one of which substantially surrounds said primary ionization electrodes, energizing means for establishing a relatively higher difference of potential than that applied between said prirnary ionization electrodes between said electrodes other than said primary ionization electrodes to produce a region of secondary ionization between said work anode and said control electrode for co-action with said primary ionization, a resonant circuit included between the secondary ionization electrode having the highest potential and the primary ionization electrode of highest potential, a circuit included between the secondary ionization electrode having the lower potential and the primary ionization electrode of highest potential, said circuits being intercoupled to produce a regenerative eiTect therebetween.

5. In an oscillator system, a partially evacuated envelope, a pair of ionizing electrodes within said envelope, a control electrode and a work anode substantially vco-axial with said ionizing electrodes, means including said ionizing electrodes for producing therebetween a region of ionization activity, means including said control electrode and said work anode for producing therebetween a secondary region of ionization activit said two regions of ionization activity being substantially oo-axial and co-extensive, and means for producing regeneration between the electrodes utilized for producing one of said regions of ionization activity. I

AUGUST HUND. 

